1. Field of the Invention
The present invention relates to a failure recovery method in an Ethernet ring network, and more particularly to, a failure recovery method in a non-revertive mode where, instead of a master node, a node, in which a failure has occurred, has blocked ports after recovering from the failure.
The present invention is derived from a research project supported by the Information Technology (IT) Research & Development (R&D) program of the Ministry of Knowledge Economy (MKE) and the Institute for Information Technology Advancement (IITA) [2005-S-102-03, Development of Carrier Class Ethernet Technology].
2. Description of the Related Art
A conventional failure recovery method is classified into a revertive mode and a non-revertive mode. The revertive mode returns to a network, which was being used prior to a failure occurring, in which one or two master nodes have blocked ports, whereas in the non-revertive mode, instead of a master node, a node, in which a failure has occurred, has blocked ports.
More specifically, in the revertive mode, when a failure occurs in any one link in an Ethernet ring network where a master node including logically blocked links or ports exists, a blocking in the master node is removed and the link, where a failure occurred, is physically or logically blocked, thereby preventing infinite loop. Then, when the failed link is recovered, the blocked links or ports are established in the master node.
In the non-revertive mode, when a failure occurs in any one link in an Ethernet ring network and then, the failed link is recovered, both side nodes of the failed link located nearest in any one direction from the master node are selected as the blocked ports.
The Ethernet ring network having the blocking is similar to a linear network. Therefore, when such a conventional method is used, the blocked ports or the blocked links are not distributed in the Ethernet ring network and are centered only on the master node or the nodes that are near to the master node. In addition, when new information about a forwarding table is needed in the conventional method, a large amount of information is required in the links that are far from the blocked ports or the blocked links and a small amount of information is required in the links that are near to the master node so that capacities of the links are non-uniform. Also, when a failure occurs in the link of the master node, a processing method thereof becomes complicated.